I will start with I almost always export from source in/out, and that possibly doesn't matter here. However, if I leave the playhead at a certain point on the timeline, will that be the "thumbnail" frame? If not, could that be a possibility?
Not sure if that could be a metadata feature so you could control that functionality. Currently, our team uses OneDrive and SharePoint for client delivery, where everything is controlled by the company. The process of selecting thumbnails is attrocious on our company network., and having that ability to select the thumbnail upon export, would be super clean.
Alos, we have met with people within adobe, to talk about enterprise Frame.io so this would be a big win for our team!
...all of this over thumbnails lol